Formulations for asphalt and heavy oil degreasers, capable of removing and recovering heavy oils from oil sludges left in process equipment, e.g., oil storage tanks, are known. The conventional asphalt and heavy oil degreaser compositions contain so-called "alkaline builders." Moreover, many asphalt and heavy oil degreaser compositions include halogens which are undesirable for steel process equipment degreasers, because the halogens may contribute to stress cracking of the metal. Many asphalt and heavy oil degreasers only work at full strength, and are ineffective when diluted by residual liquids contained within the process equipment being cleaned. Conventional asphalt and heavy oil removers generally are incapable of absorbing and/or neutralizing the toxic gases and vapors which have accumulated within fouled process equipment. Finally, many of the asphalt and heavy oil degreaser compositions of the prior art are toxic and not biodegradable.
U.S. Pat. No. 5,085,710 to Goss discloses a composition for removing oil sludges utilizing an alkylphenol adduct and a castor oil etholylate. U.S. Pat. No. 5,389,156 to Mehta et al discloses a heavy oil degreaser including a terpene and a second nonionic co-surfactant from the family of ethylene oxide/propylene oxide polyol adducts. These disclosed formulations suffer from a number of the undesirable characteristics listed above.
It would be desirable to prepare an asphalt and heavy oil degreaser composition that is free from alkaline builders and halogens, effective even at significant levels of dilution, capable of absorbing toxic gases and vapors such as hydrogen sulfide and benzene, nontoxic, and biodegradable.